The term “spread operator” is kind of an “umbrella term” that refers to various syntactic constructs in ES6 which all look like …x. MDN does the same. However, this is misguiding, because … is not an operator (at least not in the sense the ECMAScript spec uses the term “operator”). It doesn’t generate a value … Read more
You have to return something from the callback of the outer find. In fact, for the inner iteration you shouldn’t use find but rather some that returns a boolean for whether an element matching the condition exists within the arrray: products.find((product) => { return product.items.some((item) => { //^^^^^^ return item.name === ‘milk’; }); }); or … Read more
The two pretty heavy bugs I ran into here, namely the direct export of an ES6 class with a static property and a problem with the ES6 constructor are discussed in the answers of this thread and can be found on GitHub explicitly here (export bug) and here (constructor bug). (GitHub Issue Tracker has been … Read more
When the D module is executed, the console will print this message: A evaluated A constructor Which means that the A module was evaluated only once, even if it was imported multiple times by other modules. The evaluation rules for ES6 modules is the same as for commonjs format: A module is a piece of … Read more
Unlike regular scripts, ES6 modules are subject to same-origin policy. This means that you cannot import them from the file system or cross-origin without a CORS header (which cannot be set for local files). Basically you need to run this code from a (local) server or disable same-origin in the browser for testing (do not … Read more
The correct syntax to import both default and named exports from ES6 module is to pass the default name (whatever one wants), and named, not-default modules separated by a comma: Example: index.js import browsers, { otherValue } from ‘./browsers’; in an exemplary file tree: . └── src ├── browsers.js └── index.js Often encountered real life … Read more
The closest you can get is: let object = new Map([ [‘foo’, ‘bar’], [‘1’, 42] ]); Important things to notice: Object properties are identified by strings, while Map keys can be any value, so make sure all keys are strings in the input array. Iterating a Map object yields entries by insertion order. That is … Read more
There is no opposition between these two techniques: they coexist together complementing each other nicely. Promises allows you to get the result of an asynchronous operation which is not available yet. It solves the Pyramid of Doom problem. So instead of: function ourImportantFunction(callback) { //… some code 1 task1(function(val1) { //… some code 2 task2(val1, … Read more
Got it here : credentials: ‘include’ and not withCredentials: true
Why arguments is not defined in arrow function in ES6? [duplicate]